In the trend of environmental protection, bicycles are widely used as personal transportation means. To help bicycle riders in difficult situations, such as moving uphill, an electrical motor may be mounted to the bicycle to generate additional torque to the bicycle wheels. The motor is usually powered by a battery set which has a limited power supply. Thus, the power of the battery set must be conserved and consumed in an efficient way. A manual control may be mounted in the frame and operated by the rider in order to selectively turn on/off the motor. The manual control cannot responds automatically to different riding situations by changing power output of the motor and thus may cause waste of the power of the battery set. Furthermore, manually controlling the motor while watching the traffic condition may be difficult for some riders and accidents may result therefrom.
Taiwan Patent Application No. 84215538 discloses a device for controlling the motor of the bicycle. Such a device is in general ineffective in controlling the motor. U.S. Pat. No. 5,900,703 also discloses a device to control the motor. The device cannot control the output power of the motor and thus may still cause waste of power.
Thus, it is desired to provide a torque detection device that allows a motor of a power-assisted bicycle to be controlled based on torque applied by a rider to the bicycle for overcoming the above problems.